A Preliminary Geochemical and Isotopic Appraisal of Sea Water Intrusion in the Fushë Kuqe Aquifer (Northwestern Albania)

The Fushë Kuqe costal aquifer is a typical confined alluvial aquifer. The aquifer medium consists of sand-gravel and silt-clay layers intercalation which gave it a multilayer character. The aquifer recharge occurs mainly by water infiltration from the Rver Mat in the North, and from River Droja in the South. The water flow direction is from northeast to southwest and from southeast to northwest, discharging to the Adriatic Sea. Based on the chloride and TDS (Total Solids Dissolved) content in groundwater, an advancement of sea water intrusion into aquifer was evidenced. The direction of sea water wedge is from coastal south-western sectors towards the north-eastern ones. Sample No. 6, 8, 9 and 10 show chloride concentrations over 100 mg/L and Na/Cl ratios less than 0.86 implying that the groundwater is impacted by sea water intrusion. SR (Simpson Ratio) values of 1.15 and 1.09 for water sample No. 8 and 10 are indications of a slight seawater influence, while groundwater of sample no. 6 and 9 have SR values of 6.02 and 12.35 which are typical for a highly contamination by sea water. All the points of sampled groundwater fall above the GMWL, indicating that they have suffered a preliminary evaporation before entering the aquifer, likely in the hydropower lakes of Ulza and Shkopet upstream the River Mat course. Despite the narrow range of δ¹⁸O and δ²H values (-6.80‰ to -8.00‰ and -54.00‰ to 42.00‰, respectively), the points of sample No. 6, 8, 9, 10 fall on the fresh water-seawater mixing line, indicating the influence of the seawater intrusion.